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blower motor for heater getting weak

Discussion in 'Chevy Trucks' started by chris694205, Nov 29, 2010.

  1. chris694205

    chris694205 Senior Member
    Messages: 175

    hey guys,

    I am beginning to notice on my 97 2500 silverado, that the heat that blows out of the vents is getting weaker and weaker. Its like the blower motor is getting weak but thats not the problem because I recently replaced it. Have any of you guys experienced that, if so how did you fix it
     
  2. RBRONKEMA GHTFD

    RBRONKEMA GHTFD 2000 Club Member
    Messages: 2,592

    Cabin air filter could be clogged. I would check there. Do a search on here and it will turn up.
     
  3. BlizzardBeater

    BlizzardBeater Senior Member
    from Maine
    Messages: 420

    More than likely it's the cabin air filter if the volume of air is gettng weak. If the temperature is what is getting weak, try flushing out the heater core. Are all speeds on the blower working? Are certain speeds working better than others? Does the heater work better on defrost or other settings?
     
  4. chris694205

    chris694205 Senior Member
    Messages: 175

    i would say that defrost works a little better and all of the speeds work.. the heat is hot as hell just the air flow is low.. from my understanding only 98-02 have cabin air filters??? is that right or not
     
  5. RBRONKEMA GHTFD

    RBRONKEMA GHTFD 2000 Club Member
    Messages: 2,592

    Yes it is, i believe the 88 thru 00 classics had them too.
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The GMT400's didn't have cabin filters.

    Does the motor sound like it's really flowing air yet it's not coming out the vents? Or does the motor itself sound weak?
     
  7. chris694205

    chris694205 Senior Member
    Messages: 175

    yea the motor sounds like its working fine.. just the air coming out of the vents has gotten weak over the years
     
  8. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    what if it is the speeds? mine the last couple winters has been sketchy about turning the fan on. Now that it's cold and I'm using heat again I remembered needing to fix it last winter and forgetting. Occasionally the blower works, but usually I turn the switch up the fan doesn't come on, or only comes on in one position or another. Sometimes a judicious punch to the dashboard will correct it, but not always. And sometimes after driving the fan will just start up by itself. I feel like it's probably the dash switch itself, but I'd love to hear if someone has had this problem also.
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Can you select all three outlet positions...floor, defrost, and dash outlets?
     
  10. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Likely needs the blower motor replaced but before doing so check the connector plug on the blower resistor to be sure it's not burnt/melted thus making poor connection, somewhat common issue as these old trucks age. You can access it by removing the glove compartment, it's located right on top of the HVAC box just a little to the left of the glove compartment opening.
     
  11. chris694205

    chris694205 Senior Member
    Messages: 175

    yes i can select all of the functions... i just replaced the blower motor out of another truck that my buddy has for parts. I was thinking that one could be weak to but i tried it before i took it out and it blew pretty strong out of his truck
     
  12. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Replace the motor with a NEW one (they're not overly expensive) Chris and while it's out clean out the HVAC box with a shop vac or at least some compressed air to remove any debris that may be restricting the fresh air intake. Wouldn't hurt to pull the cowl panel trim (at the base of the windshield) and check/clean it out of any leave or debris as well. You'd be surprised at how much debris will accumulate in there over the years.
     
  13. tracerich

    tracerich Member
    from Earth
    Messages: 33

    I've seen evaporator cores leak and get buildup of debris, resulting in a blockage of air.
     
  14. tac48

    tac48 Member
    Messages: 41

    Does there always seem to be more air flow out the the defrost even though it switches modes? My 98 silverado had a problem with the mode door/ valve in the heater case. I could never seem to get enough heat on the floor vents. I had more air out the defrost and dash vents. I found the rubber around the mode door/valve became deteriorated and broke off. This missing material around the outside of the door/valve allowed more air to bypass the door/valve be directed to the defrost and vents regardless of the mode selected. It eventually allowed the door to move in its retainers enough to slide out and get stuck. Had to remove the dash and heater case to repair. This is quite common, but most people don't really notice it. If you remove the very bottom center heat duct (one or two screws) you can shine a light up into the case and inspect it. Kind of hard to explain, but may be similar to what is going on with your truck. You could also take the blower motor back out and see if you can see any blockage/debris on the heater or evaporator core like was mentioned earlier.
     
  15. welded wrenches

    welded wrenches Senior Member
    Messages: 177

    replying to heat blower;

    may try running a xtra ground wire directly to blower motor and negative on battery.
     
  16. Holland

    Holland Senior Member
    Messages: 605

    Im not saying your blower motor isnt bad but i have also seen what tac48 is talking about. one of the mode doors have a bad habit of falling off its inner hinge and wedging itself crooked in the air distribution box. They'll kick little air out of the vents facing the driver and passenger but seem to work fine on defrost and floor. if you look at the driver side of the hvac assembly you can see the mode actuator and the linkage. One actuator runs both doors. one will be crooked if this is your problem. Good luck
     
  17. chris694205

    chris694205 Senior Member
    Messages: 175

    thanks for the comments... i have ordered a new blower motor just in case (only 55 bucks). but i think its probably the problem that you guys are talking about with the hinged doors getting jammed up. Im going to check into that tomorrow and will let you know. thanks again
     
  18. auto tech

    auto tech Junior Member
    Messages: 12

    grime,dust stick to the front of the heater core,spray heater core with some pinkstuff,let it set a while try to get a toothbrush at and then rinse off with water it will run out the a/c drain.it cant pull enuf air threw the heater core.
     
  19. RacingZR

    RacingZR Senior Member
    from Maine
    Messages: 399

    If you suspect a heater core issue, flush just the heater core. Prestone has a flush kit sold everywhere, even Wal-Mart. Flush with water from a garden hose- do it 2 or 3 times. When you re-install the heater core lines, reverse them (reversing the flow through the core).
    $3 for the flush and $10 for a gallon antifreeze..........no parts to throw at it.
     
  20. auto tech

    auto tech Junior Member
    Messages: 12

    its not an internal heater core prob its external the prob is not that the air is cold which would be a plugged heater core its the fact that the air is not getting pulled threw the heater core